In a liquid crystal display device, a thin film transistor (TFT) substrate on which a pixel electrode and a thin film transistor (TFT) and others are formed in a matrix and a counter substrate on which a color filter and others are formed in a location corresponding to the pixel electrode of the TFT substrate opposite to the TFT substrate are installed, and liquid crystal is held between the TFT substrate and the counter substrate. An image is formed by controlling the transmissivity of light in a liquid crystal molecule every pixel.
Since the liquid crystal display device is flat and light, the application of it spreads in various fields such as a large display device including TV, a cellular phone and a digital still camera (DSC). In the meantime, the liquid crystal display device has a problem related to an angle of visibility. A characteristic of an angle of visibility is a phenomenon that luminance varies and chromaticity varies between a case in which a screen is viewed from the front and a case in which the screen is viewed from an oblique direction. In plane switching (IPS) that operates a liquid crystal molecule by a horizontal electric field has an excellent characteristic of an angle of visibility.
Although the IPS has various methods, they are the mainstream because a pixel electrode having a slit or a counter electrode is formed on a counter electrode formed flatly and solidly or a pixel electrode via an interlayer insulation film and the method of turning a liquid crystal molecule by a line of electric force passing the slit can enhance transmissivity. A pixel structure is disclosed in JP-A No. 2010-8999 in which the occurrence of a domain is inhibited and transmissivity is enhanced in IPS having such configuration.
In configurations in JP-A No. 2010-8999 and in JP-A No. 2009-47839, transmissivity in a circumference of a pixel is enhanced by specifying mutual contours of a pixel electrode and a counter electrode. In the meantime, the pixel electrode is required to be connected to a source electrode of TFT via a contact hole. An organic passivation film is formed to flatten a surface on the TFT. To make contact between the source electrode and the pixel electrode, the contact hole is required to be formed in the organic passivation film. To prevent the disconnection of the pixel electrode, it is desirable that the cone angle of the contact hole is 45 degrees or less. Then, an upper hole of the contact hole has a large area.
An alignment film is formed on the pixel electrode to initially orient a liquid crystal molecule. Heretofore, a rubbing process has been performed to provide an orientation characteristic to the alignment film. However, since the contact hole is concave, a satisfactory rubbing orientation process cannot be applied to the alignment film in this part and orientation control cannot be applied to liquid crystal. Accordingly, in the part of the contact hole, the leakage of light by the disarray in orientation of liquid crystal is caused and image quality such as contrast ratio is deteriorated. To prevent this, a shading film has been heretofore formed to cover a contact hole area. However, the shading film naturally deteriorates a numerical aperture of a pixel and accordingly, deteriorates transmissivity and the luminance of a screen.